Comparison of Two One-Dimensional Nitrogen Leaching Models at the Watershed Scale

Abstract

The objective of this paper is to compare results obtained by two one-dimensional Nitrogen Leaching Models at the watershed scale. The models MACRO and SOIL are one-dimensional models, describing water flow in a soil profile. Both models use the SOILN model to describe the fate of nitrogen. These models include horizontal fluxes to field drainage systems and, consequently, they are field-scale rather than pure one-dimensional models. This fact enables them to be used at the watershed scale assuming that the watershed consists of different fields that do not interact. This investigation shows that one-dimensional models MACRO, SOIL, and SOILN may be used at the watershed scale after adaptation. Comparison of the results obtained by the SOIL model with those of the MACRO model indicated that both models simulate water flow with adequate precision. The results also showed that use of dual-porosity soil profile in the MACRO model with the corresponding SOILN model improve simulation of daily concentrations significantly. Thus, the MACRO model is preferable to the SOIL for simulation of daily concentrations. Both models can be used for the simulation of the mean concentrations for a longer period (2–3 months).